Dental syringe



Aug. ,1,1944.` R. E. BRUCKNER 2,354,649

DENTAL SYRINGE Filed Feb. 8, 194,15

35 rfb-CD. Q f y a?" *g W23@- glu/um Rober/fili. @rz/ciglia? alim/manPatented Aug. 1, 1944 asgsiel'l y DENTAL Simmern, y

1 notation of'ruinois Application The present invention relates todental syringes, and is a continuation-.impart of .my copendingapplication, Serial No. 412,510, viiled September 26, 1941.3Morey-particularly the invention. pertains toanovel form of plunger andpiston assembly, designed-to prevent the disruptive wedging forcesoccurring lwith axial misalignment ofthe plunger andbarrel of a syringe.s l f y ..Certaingftypes .of syrmgesare'so constructed thattheyaccomrnodate insertable glass vials have ing a rubber plug closureat each end of the vial. rDhedischa-rge endof the syringe is providedwith afhollow needle which punctures one of the plugs, while'theopposite end of the syringe' is provided withafinger grip and.' plunger,the latter being slidable axially of the vial and engageable with theLother Vof the plugs, said other plug then acting as a piston ,to,.ejectfluid vfrom the vial. Ilhe `conventional plunger employed4 is made ofone piece and at times, ybecause of a loose t inits bearing, orbecausethebearing is misaligned with respectto thevial, exerts wedgingactionresultingin'. a radial pressureagainst the wall-of the giass vialsum'cient to b reak theyial.

One of the objects of this invention is to pro-M vide a plungernorasyringerof the type referred to which permits self-adjustment of theplunger head with respect to the vial and piston and thus eliminatesthose side thrusts or strains on the vial walls, due to this wedgingaction.

Another object of the invention is to provide a plunger made in twoparts and having a swivel connection between the two parts. Since theplunger head is free to swivel slightly relative to the piston, thereresults a three link kinematic chain, comprising the piston and the twoparts of the plunger, in contrast with the self jamming of the two linktrains of the prior art.

Other objects will be apparent from the following description of thesyringe, reference being made to the accompanying, drawing in which Fig.1 is a longitudinal section of a syringe embodying the invention;

Fig. 2 is an enlarged section through the sleeve used to clamp the vialin the syringe barrel;

Fig. 3 is a top plan view of the clamping sleeve;

Fig. 4 is an enlarged transverse section taken on line 4-4 of Fig. 1;

Fig. 5 is a diagrammatic illustration of.` fthe plunger embodied in thepresent invention showing its relation to a vial and piston therein,constituting a three link kinematic train.

In the drawing, the barrel I0 is provided with an opening Il on one sidethereof to permitirlsertion of the vial I2, and is out away on its op-RebertE. BrucknenVinelandf-N. .1.,yassignerito,n u l v r, VKimble GlassCompany, Vineland, N. VJ., acori-V .Februarya 1943seria1 N0.- 475,1511In Canada March 4, A1942 posite side at I3 to accommodate aspiring.linger I4 bearing against the vial. The'lower end of'the I5'and threadedat IIto` barrelis reduced as at receive capii, the latter having a boreI8 to accommodate a hollow and has a partially vspherical medialportion.22 bearing against seats23 and 24 in the endsof the reducedvbarrel portion and' cap, respectively, .so that it is clampedtherebetween. The kupper end of the barrel is threaded at 25 to permitattachment of threadedcap 26having a nger .grip21- thereon. An annularsleeve 28 is axially slidable in the upper'partof th urged into engagingrelation with vial I2 by spring, 25 bearing its other end against capr26.V Thesleeve-thus clamps the vial in the barrel. It is to be'notedthat the sleeve is conically beveled at 3I, ;3I- so that it isreversible and accommodatesy itself to the vial Vaswell as to thespring. Y,The sleeve is iurt` errnore provided with a longitudinalrecess 32l to receive the upper end of spring, I4. l

the vial. The :dared end of the plunger head is also engageable in oneposition thereof with sleeve 23 to elevate the sleeve against spring 29and permit insertion of the vial in the syringe barrel. The diameters ofhead 3'I and ared portion 38 are both somewhat less than that of piston34 and the internal diameter of vial I2. The end surface of the head issmooth and in contact with the piston 34 when transmitting axial thrustbut is free' to slide or swivel relative to the piston. When adjustingitself to misalignment the smooth end surface 38 of the plunger head isfree to slide on the face of the plug piston 34, then permitting theplunger head to center itself with respect to the piston and the vial sothat lateral thrusts on the piston are greatly reduced or entirelyremoved. This eliminates the disruptive wedging needle I9. The needlealsof passes through bore-'2| in the reduced portion: I5'- barrel,vbeing normally4 at `one endagainst the sleeve and atv K -heviaLbeOreitsv insertion Lin; thejsyringe barrel, is closed at itsends byplugs33,. 34; ,Plugwith suiiicientclearance to permit plunger. Thus,regardless of whether :the

the two parts of the Having described my invention what I claim 4 as newand desire to secure by Letters Patent 1. A dental syringe or the like,comprising a container for a liquid, a piston in said container, aplunger separate from said piston and adapted to move vsaid pistonlongitudinally of the container to eject liquid therefrom, saidplungercomprising a two-part rod, the diameter of said plunger being less thanthat of said container,

' and a swivel connection between the parts of the rrod. i

plunger rod is somewhat canted or axially misaligned with the vial, theplunger head, the diameter of 'Whichis less than that of the vial, is

permitted some free laterally slidable movement f with respect to theplunger. tov compensateior axial misalignment. The piston 34 being made:f

from resilient material, such as rubber, absorbs small lateraldisplacements transmitted thereto, but eveniif. the plug be made of amore: or less rigidmateria-l, the three. linkv kinematic train wouldpermit the head to4 adjust itself laterally Without self-jamming orwedging action against thewall of thev vial. This is not possible withtheone.. link or vtwo link trains of the prior art. Hencejvthe tendencyfor the end of the plunger to exert a disruptive wedging side thrustagainst the Wallsv ofthe vial the vial prevented.

From Fig. 5, which illustratesl the. present invention, it will beseenthat. the head 31 is swiveled at- 39 to the end-of the plunger 35and is separate from but bears against piston 34` and thatits' diameteris less than that of the vial. Hence the assembly constitutes athree'link kinematic train which is free' to run down through thevial-without any selfjamming or locking or wedging action. Whileapreferred form of theinvention has beenv described and illustrated, itis not intended that the' invention be limited to the exactk detailsshown. -The two-part plungerv may obviously be used with other types ofsyringes and the manner' of connectingv the parts -ofr the plungerchanged if desired.

is obviated and breakage of v 2. A dental syringeor the like, comprisinga l'container for a liquid, a piston in said container,

a plunger separate from said piston and adapted to move said pistonlongitudinally of the container to eject liquid therefrom, said plungercomprising `a `two-part rod, the diameter of said' plunger being lessthan that of said container, and a ball and socket connection betweenthe parts ofthe rod.

3. A dental syringe or the like, comprising a.

container for a liquid,v a piston in said container,` said piston beingformed of resilient materiah'a plunger separate from said piston andadapted to move said piston longitudinally of the container to ejectliquid therefrom,4 said. plunger comprising a two-part rod, the diameterof said. plunger being less than that of said container, and a swivelconnection between the parts of -thef` rod. v

4. A dental syringe or the like, comprising a container for a liquid, asaid piston being formed ofrresilient material, a plunger separate fromsaid piston and adapted to move said piston longitudinally of thecontainer to eject liquid' therefrom, said plunger havi-ng adiameterless than'that of said container and comprising artWo-part rod', oneportion of the rodhaving asubstantially vspherical end, the otherportion ofsaid rod having a substantially spherical recess, saidrecessed end andvsaid spherical end cooperating to form a ball andsocket con'- nection between said portions'l ROBERT E. BRUCKNER.

piston. in said container,-

